Fix scala style.

python/pyspark/sql/functions.py

@@ -144,7 +144,7 @@ def _():
              'polar coordinates (r, theta).',
     'hypot': 'Computes `sqrt(a^2^ + b^2^)` without intermediate overflow or underflow.',
     'pow': 'Returns the value of the first argument raised to the power of the second argument.',
-    'logarithm': 'Returns the first argument-based logarithm of the second argument',
+    'log': 'Returns the first argument-based logarithm of the second argument',
 }
 
 _window_functions = {

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala

@@ -204,7 +204,7 @@ case class Pow(left: Expression, right: Expression)
 }
 
 object Logarithm {
-  def apply(exprs: Seq[Expression]) = {
+  def apply(exprs: Seq[Expression]): Expression = {
     if (exprs.length == 1) {
       new Log(exprs(0))
     } else if (exprs.length == 2) {
@@ -213,7 +213,7 @@ object Logarithm {
       sys.error(s"Log only accepts two input expressions")
     }
   }
-  def apply(child: Expression) = new Log(child)
+  def apply(child: Expression): Expression = new Log(child)
 }
 
 case class Logarithm(left: Expression, right: Expression)

sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala

@@ -96,6 +96,7 @@ class DataFrameFunctionsSuite extends QueryTest {
     checkAnswer(
       df.select(org.apache.spark.sql.functions.log("a"),
       org.apache.spark.sql.functions.log(2.0, "a"),
-      org.apache.spark.sql.functions.log("b")), Row(math.log(123), math.log(123) / math.log(2), null))
+      org.apache.spark.sql.functions.log("b")),
+      Row(math.log(123), math.log(123) / math.log(2), null))
   }
 }